This invention relates to a needle selection device of the type used in a knitting machine and, more particularly, to such a device which is electromagnetically controlled and is used in a circular knitting machine to select the needles carried by one of a pair of revolving needle carriers, known as dial needles. This invention is particularly useful in knitting machines that are readily adapted to produce patterned fabrics, selvedged fabrics or other conventional knitted fabrics for typical body sizes, as well as fabrics of higher gauges.
Circular knitting machines are particularly adapted for attractive designs, such as Jacquard designs. Typically, needle selection for executing such designs by circular knitting machines is carried out by way of mechanical or electromagnetic selector devices. However, most of these selector devices have been designed to select needles which are mounted as so-called "cylinder needles", and are not easily adapted for use with so-called "dial needles" that advantageously are carried by some circular knitting machines.
A mechanical pattern-forming device is known from U.S. Pat. No. 3,646,779 in which a mechanism of the type that has been used to knit a pattern by way of "cylinder needles" operates with "dial needles" to produce knitted fabrics with patterns on both sides (or surfaces). In one embodiment, selectors which operate (e.g. they move or pivot) in accordance with the pattern being knitted drive jacks which, in turn, move dial needles associated with those jacks into knitting position. As one example, the selectors raise the jacks which, in turn, move the knitting needles. However, this mechanical pattern producing device with its needle selection mechanism is of relatively complex structure and limits the possibilities of needle selection. This device is better suited for use with multi-feed circular knitting machines whose needles are mounted in needle carriers, so-called cylinder and dial, of rather large diameter.
In addition to the aforementioned mechanical selection device, electromagnetic selection apparatus is known from Swiss Pat. No. 213,033 for use with needles arranged in a ring (referred to herein as dial needles). In this electromagnetic selector, a magnet is used to move control elements of a pattern wheel, these elements being shifted into a guide way, thereby moving the knitting needles into operating position. The pattern wheel typically is disposed behind the dial needles, and the direct movement of the control elements of this wheel under the action of the selector magnet may require a high degree of accuracy and precise tolerances of the individual operating elements. Furthermore, this device generally needs a considerable amount of space in the interior of the ring of needles or dial.